Markets news on stocks, currencies and oil; Ratings agency Standard & Poor's today cut the ratings on several Irish banks, saying that it has concluded that their asset quality and earnings will likely remain under significant pressure over the medium term. Meanwhile, Tullow Oil plc today announced that its subsidiary, Tullow Uganda Limited has entered into a Sale and Purchase agreement (SPA) with Heritage Oil & Gas Limited (HOGL) and Heritage Oil Plc (Heritage) to purchase their entire interest in Block 1 and Block 3A in Uganda. This follows Tullow exercising its right of pre-emption on 17 January 2010 and the approval of the transaction by Heritage shareholders yesterday.